Individuals with Primary Fibromyalgia Syndrome (PFS), who experience widespread musculoskeletal pain in the absence of detectable inflammatory disease, are often disabled and frequent users of health care services. Yet little research has been done on psychosocial processes that accompany, stem from, or affect this disorder. The broad objectives of the proposed research are to explore the temporal patterning of symptoms and psychological states among individuals with PFS and identify factors that account for individual differences in linkages between symptom and psychological processes. The specific aims are (1) to document similarities and individual differences in fibromyalgia pain across and within days; the relations between pain and mood across and within days; and the relations of daily pain with nonrestorative sleep, pain cognitions, and the occurrence of distress- eliciting daily events; (2) to evaluate support for the general hypothesis that psychological dispositions, affective disorder, tender point thresholds, and status as a rheumatology patient predict individual differences in patterning of these daily processes; and (3) to address methodological questions including the effect of daily self- monitoring on daily process measures and the magnitude and sources of inaccuracy in retrospective symptom reports. One hundred individuals with PFS (half of whom will be referred by rheumatologists) will be studied for 50 consecutive days. Each morning they will describe the previous night's sleep; on each of five occasions during the day, they will rate their regional pain and mood; and each night they will describe the most bothersome events of the day and answer a questionnaire concerning their thoughts and feelings about the day's pain. To encourage and monitor compliance, participants will record their responses on hand-held computers controlled by a self- monitoring program designed for this study. Personality traits, tender point thresholds, and symptoms of affective disorder will also be assessed as predictors of daily variables and their interrelations. Fifty additional subjects will be assigned to a control group without daily self-monitoring in order to evaluate possible reactive effects of the data collection procedure. Data analytic procedures feature the statistical modeling of each participant's time series and testing regression models that account for individual differences in time series models.